I do have to say that's a nice UU layout

I got a few suggestions:
The Dark Trooper didn't appear until after the Battle of Endor, IIRC. Perhaps it could be a ground UU for the Remnant while the stormtrooper is the Imperial ground UU in its place.
The Eclipse and Executor SSDs are not the same. The Executor, IMO is a better choice as a UU since the Eclipse models were pretty much superweapons.
I don't know a whole lot about the Ancient Old Republic, but the Interdictor cruiser wasn't produced until Palpatine had already come to power, and the A-wing fighter after that, sometime between the Battles of Hoth and Endor.
The E-wing would, IMO, be a better fit as NR space UU than the B-wing. It was, after all, the successor to the X-wing. Both Rebels and NR should have Bothan Spies as a ground UU. It would make things really interesting if you were to play with both. Perhaps a second Rebel ground UU could be the Snowspeeder.
The Ancient Old Republic could use the Dreadnought as one of its space UUs, and maybe the Z-95 as another. The Galactic Senate (Old Republic lol) could use the ARC-170 as one of its space UUs
Ehhh to make it simple, here's what I'm suggesting:
Ancient Old Republic
Ground UU1: Jedi Master
Ground UU2: Rocket Jumper
Space UU1: Dreadnought
Space UU2: Z-95 Headhunter
Galactic Senate
Ground UU1: Clone Trooper
Ground UU2: AT-TE
Space UU1: ARC-170
Space UU2: Acclamator Assault Ship
Galactic Empire
Ground UU1: Stormtrooper
Ground UU2: AT-AT (symbolizes the might of the Empire - the AT-IC could be an anti-starship weapon)
Space UU1: Executor-class Star Destroyer
Space UU2: TIE Interceptor
Imperial Remnant
Ground UU1: Dark Trooper
Ground UU2:
Space UU1: TIE Defender
Space UU2: Executor-class Star Destroyer (the Remnant used the same capital ship designs)
Rebel Alliance
Ground UU1: Bothan Spy
Ground UU2: Snowspeeder
Space UU1: X-wing
Space UU2: Mon Calamari Star Cruiser
New Republic
Ground UU1: Bothan Spy
Ground UU2: Jedi Master
Space UU1: E-wing
Space UU2: Mon Calamari Star Defender (or MC-90 Star Cruiser)
I also suggest the Rakamat as the second Yuuzhan Vong ground UU.
That's all I can think of right now and like I said, that's pretty good work - especially the CIS, there isn't a recognizable unit they don't have except maybe the Battle Droids but the Droideka makes up for that
PS - I left out the Hapan Battle Dragon because I believe it could be used as a unit for a future edition of this that might include the Hapans. There are plenty of other units I can think of as well like that (Yevethan Thrustship, Ssi-Ruuvi Battle Droid, Killik Nest Ship for example)